Test pipes and O2 sensors
06-05-2003, 03:11 AM
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Test pipes and O2 sensors
If you run a test pipe in place of the cat. is there a problem with O2 sensor readings?
I've heard that you need a functional cat to "fire up" to get a good reading for the O2 sensor to work correctly.
But, I know that you can get rid of the cat and it runs better, ideas anyone?
I've heard that you need a functional cat to "fire up" to get a good reading for the O2 sensor to work correctly.
But, I know that you can get rid of the cat and it runs better, ideas anyone?
06-05-2003, 03:36 AM
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I think it is the other way around, the O2 sensor keeps the AFR at Lamda=1 (14.7/1) so that the cat can work correctly, that is why the O2 sensor was developed. The O2 sensor is located before the Cat in the 944. The closed loop control can keep the AFR within 1% if working correctly.
THe O2 sensor is normally located a foot or two from the engine, this allows the exhaust gas to heat the O2 sensor. Too close and the exhaust gas preasure can hurt the sensor, too far away and it heats up too slowly. The sensor doesn't start working correctly until it is heated to around 500 degrees. The Cat has no effect on this since it is down stream of the sensor.
THe O2 sensor is normally located a foot or two from the engine, this allows the exhaust gas to heat the O2 sensor. Too close and the exhaust gas preasure can hurt the sensor, too far away and it heats up too slowly. The sensor doesn't start working correctly until it is heated to around 500 degrees. The Cat has no effect on this since it is down stream of the sensor.